The present invention generally relates to attaching structural elements with fasteners, and more particularly to a novel fastener and method for fastening structural elements together with fasteners.
It is well known to use screws and nails, or similar pin-type fasteners, for securing floor, wall and ceiling panels to supporting structures in buildings and vehicle cargo container bodies. In the case of truck trailer bodies, hard wood floors are attached to a metal frame or substrate. The typical truck trailer body has a steel frame, and the hardwood flooring is secured to the steel frame with metal fasteners. The existing technology for securing floors to truck trailer bodies requires pre-drilling holes in both the wood flooring and the underlying metal frame, e.g., steel angle irons or junior I-beams, and using a powered screwdriver to drive to apply self-tapping screws through the pre-drilled holes to anchor the flooring to the frame. In some cases, vehicle cargo bodies or personnel-containing structures, e.g., mobile homes, may use aluminum framing. Since aluminum frame members are more easily penetrated than steel frame members of the same thickness, wood flooring and wall and ceiling panels may be attached to aluminum framing by means of nail-type pins with spiral grooves disposed along a portion of their length, with those pins being driven through the flooring and into aluminum frame members by means of a pneumatic high impact nail driver, e.g., a driver as disclosed in my U.S. Pat. No. 5,645,208, issued Jul. 8, 1997 and 4,040,554, issued Aug. 9, 1977.
However, using a pneumatic high impact nail driver has certain limitations with respect to applications involving hard wood flooring and steel framing. For one thing, the high impact produced by such a driver tends to split the hardwood flooring. Also, some steel framing members are too thin which causes bending of the steel substrate by the fasteners under the force exerted by the high impact driver. Moreover, since it is strictly a hammer-like impact procedure, when a fastener is driven through the floor into an underlying high tensile strength frame member, the fastener may or may not be driven properly to force the flooring member into a tight fit with the frame, resulting in it not passing inspection requirements. Consequently the procedure using predrilled holes and self-tapping screws has become standard industry practice. In an attempt to avoid the necessity of pre-drilling the underlying frame members, driver/fastening systems have been conceived that utilize special high carbon steel self-drilling, self-tapping screws and a high torque rotary screwdriver. However, for the most part, those systems function satisfactorily only if the underlying metal to be penetrated is a mild steel, e.g., A-36 steel, and has a maximum thickness of about xe2x85x9xe2x80x3 or less. A further impedance to use of self-drilling screws is that currently trailer body manufacturers are preferring to use a high tensile strength steel having a tensile strength of 80,000 psi and a yield strength of approximately 50,000-65,000 psi. It is difficult to reliably penetrate that steel in a thickness of xe2x85x9xe2x80x3, since in the process of attempting to do so the screws tend to burn due to the heat buildup. Therefore, there has existed a need for an improved fastening method and apparatus which can reliably attach wood flooring to high tensile strength steel substrates having a thickness in the order of xe2x85x9xe2x80x3 or thicker. Such a method and apparatus is described and illustrated in my copending U.S. patent application Ser. No. 10/195,207, filed on even date herewith for xe2x80x9cMethod And Apparatus For Attaching Structural Components With Fastenersxe2x80x9d. That method and apparatus involves use of a pneumatic rotary impact torque driver, such as the Model 2131 pneumatic driver made by Ingersoll-Rand Co. of 200 Chestnut Ridge Road, Woodcliff Lake, N.J. 07675, and self-drilling, self-tapping fasteners. That copending application is incorporated herein by reference.
One object of the invention is to provide a novel fastener for attaching structural-components, such as hard wood flooring panels, to metal substrates, the fastener combining self-drilling and self-tapping capabilities.
Another object of the invention is to provide a clip of fasteners for use with the powered torque driver apparatus disclosed in my copending U.S. patent application Ser. No. 10/195,207 or other torque drivers, the clip comprising a plastic fastener-retaining strip adapted to be supported by and move along a fastener magazine or holder into fastener-driving position relative to a driver associated with the magazine, and a plurality of self-drilling, self-tapping screw fasteners supported by the plastic strip, with the fasteners being formed so as to facilitate their removal from the plastic strip when being driven into fastening relation with structural components.
These and other objects are achieved by providing a plurality of fasteners that are formed so as to have a pointed tip, a first self-drilling portion contiguous with the pointed tip, a second self-tapping screw portion contiguous with the first drilling portion, and a head that is adapted to be rotatively driven by a torque driver. The fasteners are mounted in a plastic strip comprising a plurality of sleeve sections, each gripping and supporting a single fastener. Each fastener is formed with cutting elements around its head that operate to cut through fastener-retaining elements of the supporting strip as the fastener is driven into a work piece consisting of at least a structural component made of wood or metal and a metal substrate. Each fastener is driven into the workpiece by engaging the head of the fastener with a tool bit attached to a rotary impact driver, and operating the driver so as to rotatively drive the first self-drilling portion of the fastener into the structural component and cause that drilling portion to drill a hole through said component, and then rotatively impact drive the fastener so as to cause said fastener to penetrate and drill a hole through said substrate and make a screw connection with the substrate. Other features and advantages of the invention are described or rendered obvious by the following detailed specification.